Merge pull request #218 from munnerz/test-race

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Enable go race detector and fix race in scheduler

**What this PR does / why we need it**:

Fixes a race condition in the scheduler package and enables the race detector in tests

**Release note**:
```release-note
Fix a race condition in the package responsible for scheduling renewals
```

Makefile

@@ -76,6 +76,7 @@ $(CMDS):
 
 go_test:
 	go test -v \
+	    -race \
 		$$(go list ./... | \
 			grep -v '/vendor/' | \
 			grep -v '/test/e2e' | \

pkg/scheduler/scheduler.go

@@ -35,19 +35,18 @@ func NewScheduledWorkQueue(processFunc ProcessFunc) ScheduledWorkQueue {
 // Duration has come (since the time Add was called). If an existing Timer for
 // obj already exists, the previous timer will be cancelled.
 func (s *scheduledWorkQueue) Add(obj interface{}, duration time.Duration) {
-	s.clearTimer(obj)
+	// we call Forget before acquiring the workLock in order to avoid deadlock
+	s.Forget(obj)
+	s.workLock.Lock()
+	defer s.workLock.Unlock()
 	s.work[obj] = time.AfterFunc(duration, func() {
-		defer s.clearTimer(obj)
+		defer s.Forget(obj)
 		s.processFunc(obj)
 	})
 }
 
 // Forget will cancel the timer for the given object, if the timer exists.
 func (s *scheduledWorkQueue) Forget(obj interface{}) {
-	s.clearTimer(obj)
-}
-
-func (s *scheduledWorkQueue) clearTimer(obj interface{}) {
 	s.workLock.Lock()
 	defer s.workLock.Unlock()
 	if timer, ok := s.work[obj]; ok {